Heater tube with welded hermetic closing plate - is welded by rapidly raised current and rotation of workpieces

摘要

Covers are fitted to radiator tubes by electric arc welding. Vacuum tight closing of the heater tube inner cavities is ensured by welding the closing plates in an automatic operation independently of the difference in cross sections between the covers and the tubes. At the start of the welding operation the electrode (12) is near the region (14) of the transition of the tube section (2) and the adjacent closing section. The welding current and electrode are brought rapidly to the reqd. working current value and held there. Relative rotation of workpiece and electrode is started when the working current strength has been reached. The working current is maintained over the full circle rotation. The welding current is smoothly reduced to zero subsequently while maintaining the relative rotation between the workpiece and the electrode.